Production of hydrocarbon feedstocks for petroleum sulfonates



United States Patent 3,183,183 PRODUCTION OF HYDROCARBON FEEDSTOCKS FORPETROLEUM SULFONATES Jack A. Guthrie, Media, Pa., assignor to Sun OilCompany, Philadelphia, Pa., a corporation of New Jersey Fiied Jan. 16,1962, Ser. No. 184,867 2 Claims. (Cl. 208-311) This application is acontinuation in part of my copending application Serial Number 625,375,filed November 23, 1956, now abandoned.

This invention relates to the manufacture of sulfonic acids and saltsthereof, and more particularly to the preparation of an improvedsulfonate feed stock from petroleum oils of lubricating viscosity.

In commercial processes for the production of sulfonates from petroleumstocks, it has been the practice to first refine the stock by contactingwith a selective solvent, such as furfural, phenol, sulfur dioxide, orother solvents which preferentially dissolve aromatics, and to recover araflinate poor in aromatics, and an aromaticrich extract. The rafiinate,which may contain 5-15% of aromatics or other sulfonatable compounds, isthen treated with concentrated sulfuric acid, oleum, or sulfur trioxide.Sulfonic acids formed by this treatment are neutralized and separatedfrom the unsulfonatable oil, which is then further processed to alubricating oil.

The foregoing procedure has two main disadvantages. The first is thatthe unsulfonatable oil will retain some acidic components which,although present in very small amounts, give rise to corrosion problemsin further processing, and tend to give the finished lubricating oil anoff-color appearance. econdly, since the charge stock to the sulfonatoronly contains a small proportion of sulfonatable material, largefacilities must be provided to carry the inert material through theplant. In the past, attempts have been made to increase the amount ofsulfonates obtainable from a plant of given size by using an unrefinedpetroleum fraction of lubricating viscosity as the feed thereto. Theseattempts have not proven successful, since the unrefined crude containscomponents which form an excessive amount of heavy sludge on contactwith acid so that recovery of the valuable sulfonates is notcommercially feasible because of the problems associated With handlingand disposal of the sludge.

It is an object of this invention to provide a process for obtaininghigh quality mahogany and green acid sulfonates from an unrefinedpetroleum fraction of lubricating viscosity without adversely affectingthe properties of the fraction useful as. a lubricating oil.

It is a further object of this invention to provide a feed stock for anexisting sulfonation plant which will considerably increase theproduction of sulfonates from the plant over that obtainable when asolvent-extracted rafiinate fraction of a petroleum crude is processed.

I have found that the foregoing objects may be attained by first solventextracting a petroleum fraction of Inbricating viscosity to obtain as arafiinate the fraction which has previously been used as a sulfonationcharge stock, and which comprises 5 to 15% sulfonatable material. Thismaterial is not, however, subjected to sulfonation, but is sent directlyto lube oil processing, thus avoiding the corrosion and colordihiculties inherent in processing a lube stock which has previouslybeen subjected to sulfonation. A primary extract is recovered whichcomprises an oil of higher aromatic content than the charge to theextractor, dissolved in the major portion of the solvent. This extractis subjected to flash distillation to remove a portion of the solvent,the bottoms from the flash distillation is mixed with a quantity ofsecondary extract recovered from a later stage of the process, themixture is cooled to a temperature of from about 130 F. to 160 F., andis passed to a settler in which an upper oil layer or secondaryraffinate and a lower solvent layer will form. The lower layer istreated to separate solvent and to recover a secondary extract, aportion of which is recycled to admixture Withthe primary extract.

I have further. found that when a portion of the secondary extract isrecycled and mixed with the primary extract and the mixture subjected tosettling, that the secondary raflinate comprises from 40 to 65 volumepercent sulfonatable material. This is a much greater volume ofsulfonatable material in the sulfonate feed stock than the volumeproduced by prior art feed concentration processes and thus the processof the invention affords the production of a large volume of highquality sulfonates from a relatively small amount of oil. Furthermore,the unsulfonatable portion of the secondary raffinate provides anexcellent carrier or diluent for the sulfonate material.

The feed to the process is an unrefined petroleum fraction of thelubricating oil type. It has a viscosity ranging from to Saybolt secondsat 100 degrees R, a viscosity gravity constant of 0.820 to 0.840, aboiling range of 600 to 900 F., a specific gravity of 0.887 to 0.870.This feed contains from about 15 to about 35 volume percent aromatichydrocarbons. It is contacted with a solvent selective for aromatichydrocarbons at a temperature in the range of from about to 265 degreesF., preferably 170 to 235 degrees F. Any of the commonly used solventsfor aromatic hydrocarbons is suitable including furfural, phenol,B,B-dichloroethyl ether (Chlorex), nitrobenzene, sulfur dioxide anddiethylene-glycol. Solvent to oil ratios of 0.5 :1 to 3:1 are suitable.The primary extract is then passed to a flash tower for removal ofsolvent. From 10 to 50% of the solvent is removed. The primary extractsolution contains from 60 to 90 volume percent aromatics, and representsfrom 20-40 vol. percent of the original lube oil fraction.

The primary extract is then subjected to phase separation in aconventional settler. Phase separation is accomplished at a temperatureranging from 130 to degrees F. The bottoms from the phase separator arepassed to a flash tower and then to a stripper for the removal ofsolvent. The secondary extract recovered from the settler bottoms is thematerial recycled in the process of the invention. From 35 to 100 volumepercent (based on the primary extract) can be recycled and added to theprimary extract. As stated previously, this secondary extract is theprincipal means of adjusting the solvent to oil ratio of the primaryextract prior to phase separation. It should be kept in mind, however,that some solvent adjustment is accomplished by flashing solvent fromthe primary extract and additional solvent adjustment is accomplished bymeans of a cooler located between the flash tower of the settler. Thoseskilled in the art will understand that it is possible to correlate therecycle of secondary extract with conditions in the flash tower and thecooler in order to arrive at the opti-- mum conditions in the settler.

The secondary raffinate is removed, is steam stripped to removedissolved solvent, and is passed to a sulfonator' in which it iscontacted with concentrated sulfuric acid,

oleum, or preferably sulfur trioxide, in quantity sufficient tosulfonate the sulfonatable materials contained therein. Sulfonation maybe accomplished without dilution, but

in order to avoid emulsification and separation problems in subsequentsteps of the process, I prefer to dilute the.

secondary rafiinate prior to sulfon ation with from one to three volumesof a nonreactive cycle oil recovered from a subsequent step. After thesulfonation, the sour oil is air blown to remove sulfur dioxide andunreacted sulfur trioxide and is separated into an oil layer and asludge layer, which are separately worked up to recover mahoganysulfonates and green acid salts. The sulfonatable materials in thesecondary raifinate are similar in composition to those in the primaryraffinate heretofore used as a charge stock to a sulfonation process,since the quality of the product mahogany sulfonates is equally as good.

In order that those skilled in the art may more fully appreciate thenature of my invention and the method of carrying it out, an exampleshowing the preferred conditions of operation for a commercial operationwill be more fully described in connection with the accompanyingdrawing, which is a diagrammatic flow sheet of the invention.

A crude petroleum distillate charge stock of lubricating viscosity,boiling between about 600 F. and 900 F., is charged through line 1 tosolvent extraction tower 2, at the rate of 3600 barrels per day (b./d.).In tower 2 the charge is countercurrently contacted with furfuralintroduced into tower 2 through line 3 at the rate of 6120 b./d. Atemperature gradient is maintained in tower 2 ranging from 235 F. at thepoint of introduction of the furfural to 170 F. at the base of thetower. A primary raflinate stream comprising 2810 b./d. of oil and 420b./ d. of furfural is recovered overhead through line 4. After solventremoval and dewaxing, the primary raffinate will yield a lubricating oilcontaining from 10.5% to 13% sulfonatable material by weight. Theprimary rafiinate has in the past been used as a feed stock forsulfonation, but according to the present invention, it is passeddirectly to the lube oil processing operations.

A primary extract comprising 790 b./d. of oil and 5700 b./d. of furfuralis removed through line 5 and is passed through heater 6 to flash tower7, from which 1840 b./ d. of furfural are taken overhead through line 8.An extract concentrate comprising 790 b./d. of oil and 3860 b./d. offurfural is removed from tower '7 through line 9 and is mixed with 370b./d of secondary extract introduced through line 10, and the mixture ispassed through cooler 11, in which its temperature is reduced to 150 F.,to settler 12, in which the mixture phase separated into an upper oillayer, or secondary rafiinate, and a lower extract layer. The extractlayer, comprising 765 b./d. of oil and 3805 b./d. of furfural iscontinuously removed from settler 12 through line 13, and is passedthrough heater 14 to flash tower 15, from which the major portion of thefurfural contained in the extract phase is taken overhead through line16. The extract, containing a small amount of furfural, is then takenthrough line 17 to steam stripper 18, from which the remainder of thefurfural is removed overhead through line 19. Secondary extract, havingan aromatic content of 92% by weight, is taken oif stripper 18 asbottoms through line 20 at the rate of 765 b./d. of which 370 b./d. isdiverted by proportioning valve 21 to line for admixture with theprimary extract concentrate, while the remaining 395 b./ d. is taken offto storage or other disposal via line 22.

The secondary raflinate, comprising 395 b./d. of oil and 55 b./ d. offurfural, is removed from settler 12 through line 23 and is passed tosteam stripper 24, from which the furfural is removed overhead throughline 25. A sulfonate feed stock, containing about 50% sulfonatablematerial by weight (45% by volume), and which boils in the range of 578F. to 865+ F., is recovered from stripper 24 through line 26. This feedstock is then diluted with three volumes of an oil of the same boilingrange from line 27. The diluent oil contains essentially no sulfonatablematerial, and is recovered from a later stage of the process, as will bemore particularly described hereinafter.

The mixture of feed and diluent is then passed to sulfonator 28 in whichit is contacted and mixed with anhydrous sulfur trioxide introducedthrough line 29 in the amount of 24 pounds per barrel of the mixture ata temperature of 165 F. The sulfonation products are then passed throughline 30 to stripper 31 in which they are contacted with a stream of airfrom line 32, which serves to strip out unreacted sulfur trioxide andany sulfur dioxide formed in the reaction, these gases being taken offthrough line 33. The stripped sulfonation products are then takenthrough line 34 to settler 35, in which they are broken into an uppersour oil layer and a lower sludge layer. This latter layer, whichcontains oil and green sulfonic acids, is removed from settler 35 at therate of 140 b./ d. and is 'passed through line 36 to neutralizer 37, inwhich it is contacted with sufficient aqueous caustic soda introducedthrough line 38 to neutralize the acids and to yield a 50% aqueoussolution of sodium salts of green sulfonic acids, which is recoveredthrough line 39.

The sour'oil is taken from settler 35 through line 41, and is mixed with0.5 to 1 volume of aviation alkylate from line 42. The mixture is thenpassed to a mixer in which it is contacted with an alcoholic causticsolution from line 44. The neutralized stream passes to a settlingvessel 43 where an oil layer comprising alkylate plus unsulfonatable oilfrom the feed to sulfonator 28 is recovered through line 45, while anaqueous solution comprising mahogany sulfonates, alcohol, water, andinorganic salts, is recovered through line 46. The oil layer is passedto still 47, from which alkylate is recovered through line 42 foradmixture, after condensing, with the sour oil from settler 35, whileunsulfonatable oil is recovered as bottoms through line 48. Of this oil1185 b./d. is diverted through proportioning valve 49 to line 27 asdiluent for the secondary ratiinate, the balance being diverted throughline 50 to a later stage of the process. The mahogany sulfonate solutionis taken to still 51, in which alcohol and a portion of the Water istaken overhead through line 52A, a product comprising mahoganysulfonates, inorganic salts, and about 30% water being removed throughline 52. This product is mixed with an equal volume of isopropyl alcoholfrom line 53, and the mixture is passed to settler 54, where it isallowed to break into an upper layer consisting of a solution ofmahogany sulfonates in isopropyl alcohol and a lower brine layer, whichis Withdrawn through line 55 for further processing to recover dissolvedalcohol. The sulfonate solution in alcohol is withdrawn from settler 54through line 56 and is passed to still 57, from which alcohol isrecovered overhead through line 58. Oil from line 50 is supplied tostill 57 to yield a 60% concentrate of mahogany sulfonates in oil, whichis withdrawn through line 59 to storage.

A number of advantages are obtained by proceeding according to thepresent invention. First, production of lubricating oil from a givencharge stock may be substantially increased. In the example given, forinstance, lubricating oil production was increased by 3,455 barrels permonth by shifting from the primary raffinate to the secondary rafiinateas a feed to the sulfonation plant, while mahogany sulfonate productionremained constant. Second, corrosion of the equipment used to processthe lubricating oil is avoided. Third, the size of a plant for producinga given quantity per day of sulfonates may be considerably reduced ascompared to a plant operating on primary raffinate charge. In theexample given, the sulfonate section of the plant was designed toprocess a primary rattinate containing about 13% aromatics. Since thenew secondary raffinate charge stock contained about 50% aromatics, itwas diluted with three volumes of cycle oil to yield a feed to thesulfonator of the same character as that previously employed, in orderto fill up the plant and enable it to operate efliciently. In designinga new plant, however, the cycle oil/feed ratio could be reduced to 1:1,to reduce the liquid charged to the sulfonator by one-half, withconsequent substantial savings in plant investment and operating cost.Dilution of the feed with at least one volume of cycle oil is necessary,however, to keep the viscosity of the products from the sulfonatorwithin manageable limits. A fourth important advantage is that a largepart of the extract oil from extractor 2 is converted to sulfonationproducts far more Valuable than cracking stock, which is commonly theuse made of the extra-ct oil.

The quality of the mahogany sulfonates produced from my new charge stockis equally as good as the sulfonates made from a primary rafiinate. Acomparison of the properties of sulfonate concentrates preparedaccording to the example given above and those prepared from a primaryraflinate is shown in the following table:

Table I Charge Stock Secondary Primary Rafilnate Ratfinate SodiumSulfonatcs, Wt. Percent- 63.1 61. Sodium Garboxylates, Wt. Percen 0. 42O. 25 Oil, Wt. Percent 30. 6 33.8 Inorganic Salts, Wt. Perccnt 0. 530.83 Water, Wt. Percent 4.0 3. 4 Average Mol. Wt 448 451 Color ASTM, 15%dilute 5% 5% The quality of the green acid sulfonates produced in thepresent process is superior to that of the prior art, as

As may be observed, the green acid sulfonates produced according to myinvention contain far more sulfonates than those produced according tothe prior art, and are an acceptable commercial product, whereas thegreen acids produced from the primary raffinate were so low in sulfonatecontent as to be unsalable and had to be disposed of by dumping.

From the foregoing description, it can be seen that large quantities ofhigh quality concentrated sulfonation feed stock can be obtained byfollowing the process of the invention. While solvent modifiers andanti-solvents have been used in the past to adjust solvent to oilratios, it is believed that the employment of a recycle oil such as thesecondary extract, according to the invention, represents a distinctadvantage in that the concentrated feed stock can be sulfonated withoutfurther treatment.

I claim:

1. In a process for the preparation of feed stock for sulfonation topetroleum sulfonic acids which comprises the steps of:

(a) extracting a petroleum distillate fraction of lubricating viscosityhaving a boiling range of 600- 900 F. and containing from about 15 toabout 35 vol. percent aromatic hydrocarbons with a selective solvent foraromatic hydrocarbons at a temperature in the range of from about 150F., to about 265 F.,

(b) recovering a primary extract solution containing from to vol.percent aromatics,

(c) distilling a major proportion of the solvent from the primaryextract solution,

(d) cooling said solution,

(e) subjecting said solution to phase separation at a temperature in therange of from F. to F. to produce an oil rich secondary ratiinate and asolvent rich secondary extract,

(f) recovering the secondary raflinate as said desired sulfonation feedstock,

(g) and removing solvent from said secondary extract to render saidsecondary extract substantially solvent free, the improvement comprisingadding from 35 to 100 vol. percent of said solvent free secondaryextract to said primary extractto adjust the solvent to oil ratio forphase separation.

2. The processes according to claim 1, in which the solvent for aromatichydrocarbons is selected from the group consisting of furfural, phenoland diethylene glycol.

References Cited by the Examiner UNITED STATES PATENTS 2,514,733 7/50Vold et al 260-504 2,527,404 10/ 50 De Vault 208--311 ALPHONSO D.SULLIVAN, Primary Examiner.

1. IN A PROCESS FOR THE PREPARATION OF FEED STOCK FOR SULFONATION TOPETROLEUM SULFONIC ACIDS WHICH COMPRISES THE STEPS OF: (A) EXTRACTING APETROLEUM DISTILLATE FRACTION OF LUBRICATING VISCOSITY HAVING A BOILINGRANGE OF 600900*F. AND CONTAINING FROM ABOUT 15 TO ABOUT 35 VOL. PERCENTAROMATIC HYDROCARBONS WITH A SELECTIVE SOLVENT FOR AROMATIC HYDROCARBONSAT A TEMPERATURE IN THE RANGE OF FROM ABOUT 150*F., TO ABOUT 265*F., (B)RECOVERING A PRIMARY EXTRACT SOLUTION CONTAINING FROM 60 TO 90 VOL.PERCENT AROMATICS, (C) DISTILLING A MAJOR PORPORTION OF THE SOLVENT FROMTHE PRIMARY EXTRACT SOLUTION, (D) COOLING SAID SOLUTION, (E) SUBJECTINGSAID SOLUTION TO PHASE SEPARATION AT A TEMPERATURE IN THE RANGE OF FROM130*F. TO 160*F. TO PRODUCE AN OIL RICH SECONDARY RAFFINATE AND ASOLVENT RICH SECONDARY EXTRACT, (F) RECOVERING THE SECONDARY RAFFINATEAS SAID DESIRED SULFONATION FEED STOCK,